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    <title>第48个CSS页面</title>
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<h4>外边距折叠（合并）的计算</h4>
<p>参与折叠的外边距均为正直</p>

<div style="height: 50px; margin-bottom: 50px; width: 50px; background-color: red; border: 1px dashed blue;">A</div>
<div style="height: 50px; margin-top: 100px; width: 50px; background-color: green; border: 1px dashed blue;">B</div>


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